1. Field of the Invention
The present general inventive concept relates to a ceramic printed circuit board (PCB) and an inkjet printhead assembly. More particularly, the present general inventive concept relates to a ceramic PCB which includes a termination resistor to increase signal quality, and an inkjet printhead assembly using the ceramic PCB.
2. Description of the Related Art
Inkjet printers transmit low voltage differential signaling (LVDS) generated by drivers of main boards to head chips, namely final reception terminals, so that ink is ejected from the head chips. In order to increase signal quality, it is desirable that termination resistors for impedance matching between drivers of main boards and head chips be mounted as close as possible to areas in which head chips are mounted.
Conventionally, termination resistors have been mounted in ceramic boards through additional processes. However, if a termination resistor is mounted in a ceramic board, the termination resistor may be electrically connected to a head chip via a pad, so signal shorts may occur due to leakage of ink. Accordingly, the termination resistor needs to be separated from an ink supply path, so as to be located at a predetermined distance from the head chip, namely a final reception terminal.
However, to remove these problems, if the termination resistor is mounted in a main board, the distance between the termination resistor and the head chip may increase, so the LVDS may be distorted as illustrated in FIG. 1. FIGS. 1 and 2 illustrate graphs of signal quality measured when a conventional termination resistor is mounted in a main board. The graph of FIG. 1 illustrates the signal quality measured when the distance between the conventional termination resistor and the head chip is a certain distance referred to as S1. If the length of a cable used to connect the main board to the ceramic board is reduced in order to minimize distance S1, high frequency components may be added to the LVDS, thereby reducing the signal quality as illustrated in FIG. 2. In this situation, the distance between the conventional termination resistor and the head chip is referred to as S2 (here, S1>S2).